semilegal

As a noun legality

is lawfulness.

As an adjective semilegal is

of partial or questionable legality.

As adjectives the difference between questionable and semilegal

is that questionable is (obsolete) inviting questions; inviting inquiry while semilegal is of partial or questionable legality.

As adjectives the difference between partial and semilegal

is that partial is existing as a part or portion; incomplete while semilegal is of partial or questionable legality.

As a noun partial

is (mathematics) a partial derivative: a derivative with respect to one independent variable of a function in multiple variables.